The U.K’s National Cyber Security Centre (NCSC), the FBI and the U.S Department of Homeland Security issued a joint alert warning of a global campaign.

The alert details methods used to compromise the networking equipment used to move traffic across the net.

In a press conference about the alert, White House cyber-security coordinator, Rob Joyce, said intelligence gathered by the U.S and U.K suggested that millions of machines directing data around the net were being targeted.

Attackers also sought to undermine the firewalls and intrusion detection systems organizations used to spot malicious traffic before it reached users.

In addition, Mr Joyce said, many different organizations had come under attack for months at a time in a bid to scoop up valuable intellectual property, business information or to get at their customers.

The principal targets of the global campaign were internet service providers, firms running critical infrastructure, government departments and large companies, the alert stated.